A novel function of Rad54 protein - Stabilization of the Rad51 nucleoprotein filament
A novel function of Rad54 protein - Stabilization of the Rad51 nucleoprotein filament
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DOI：
10.1074/jbc.m212779200
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发表时间：
2003-04-18
影响因子：
4.8
通讯作者：
Kowalczykowski, SC
中科院分区：
文献类型：
--
作者：
Mazin, AV;Alexeev, AA;Kowalczykowski, SC
同源重组对于修复所有生物体中的双链DNA断裂非常重要。RAD51。和Rad54蛋白是真核生物同源重组机制的两个关键组成部分。在体外，RAD51。蛋白质与单链DNA组装形成螺旋核蛋白细丝，促进DNA链交换，这是同源重组的基本步骤。RAD54蛋白与该RAD51相互作用。核蛋白细丝并刺激其DNA配对活性，表明Rad54蛋白是参与DNA同源性搜索的核蛋白复合体的一个组成部分。在这里，使用物理标准，我们直接证明了含有等摩尔量的每种蛋白质的Rad54-RAD51-DNA核蛋白共复合物的形成。Rad54蛋白的结合显著稳定了单链或双链DNA上形成的RAD51核蛋白细丝。RAD54稳定的核蛋白细丝在DNA链交换方面更有能力，并在更广泛的溶液条件下发挥作用。因此，与RAD51互动的合作伙伴共同组装。核蛋白细丝代表了一种稳定同源重组中心生化实体的新方法，并揭示了Rad54蛋白的新功能。
Homologous recombination is important for the repair of double-stranded DNA breaks in all organisms. Rad51. and Rad54 proteins are two key components of the homologous recombination machinery in eukaryotes. In vitro, Rad51. protein assembles with single-stranded DNA to form the helical nucleoprotein filament that promotes DNA strand exchange, a basic step of homologous recombination. Rad54 protein interacts with this Rad51. nucleoprotein filament and stimulates its DNA pairing activity, suggesting that Rad54 protein is a component of the nucleoprotein complex involved in the DNA homology search. Here, using physical criteria, we demonstrate directly the formation of Rad54-Rad51-DNA nucleoprotein co-complexes that contain equimolar amounts of each protein. The binding of Rad54 protein significantly stabilizes the Rad51 nucleoprotein filament formed on either single-stranded DNA or double-stranded DNA. The Rad54-stabilized nucleoprotein filament is more competent in DNA strand exchange and acts over a broader range of solution conditions. Thus, the co-assembly of an interacting partner with the Rad51. nucleoprotein filament represents a novel means of stabilizing the biochemical entity central to homologous recombination, and reveals a new function of Rad54 protein.